Fix rename for helm dep upgrade

helm dependency upgrade wasn't working on certain file system because it assumes that os.rename is available. Since rename isn't available for subfolders in docker containers, I ripped a fallback rename strategy from dep (https://github.com/golang/dep/blob/5b1fe9e6d89372487d0aac78d9c5362a517857e7/internal/fs/fs.go#L103-L118

) that works in docker.

Signed-off-by: Brice Rising <brice.rising@slalom.com>
(cherry picked from commit 94d87ef9)